Method of making power transmission belts

ABSTRACT

A plurality of individual power transmission belts are made in a simultaneous manner utilizing the method of this invention while making full use of standard injection molding equipment. The method employs an apparatus comprised of a lower structure and an upper structure suitably fastened together and having cooperating surface means which define a plurality of annular cavities with each cavity defining an associated belt. The cavities are supplied from a common sprue and the plurality of belts are formed by the simultaneous injection of elastomeric material into such cavities and then curing and cooling the material to define the transmission belts.

United States Patent 15] 3,665,069 Richmond May 23, 1972 54] METHOD OFMAKING POWER 2,832,996 5/1958 Loftis ..18/42 TRANSNHSSION BELTS3,559,249 2/ 1971 Patton ..264/328 X 3,579,799 5/1971 Furstenburg..264/219 [72] Inventor: Kenneth D. Richmond, Nixa, Mo. [73] Assignee:Dayco Corporation, Dayton, Ohio FOREIGN PATENTS 0R APPLICATIONS Filed:Feb 1970 1,452,813 8/1966 France ..264/328 2 App], 1 1,15 PrimaryExaminerR0bert F. White Assistant Examiner-Richard R. KuciaAttorney-Reuben Wolk [52] US. Cl ..264/219, 264/262, 264/297,

264/328 57 ABSTRACT [51] Int.Cl. ..B29c 1/16 [58] Field of Search64/328, 297, 261, 262, 277, A p of mdwldufll Power transmlsswn belts aremade In 264/2|9 a simultaneous manner utilizing the method of thisinvention while making full use of standard injection molding equip- 56]References cited ment. The method employs an apparatus comprised of alower structure and an upper structure suitably fastened together UNITEDSTATES PATENTS and having cooperating surface means which define aplurality of annular cavities with each cavity defining an associated3,164,026 H1965 Terhune ..74/233 belt The cavities are pp from a commonsprue and the 3'482004 12/1969 Anderson '1' "264/25 plurality of beltsare formed by the simultaneous injection of 2351329 6/1949 Gelstenmaer'"264/262 X elastomeric material into such cavities and then curing and11932548 l0/1933 Ingwer cooling the material to define the transmissionbelts. 2,254,233 9/1941 Meyer... .....l8/3O 2,456,580 12/1948 Carter..18/59 9 Claims, 10 Drawing Figures BACKGROUND OF THE INVENTION Thepower transmission belts, such as V-belts, in present use are generallyeither formed one at a time in an associated apparatus or in thoseinstances where a plurality of belts are made in a simultaneous mannerthe plurality of belts are usually made as one elongated tubular memberknown in the art as a sleeve which must then be cut to define individualV-belts whereby the various operations required in making belts in thismanner are complicated, time consuming, and result in expensive V-belts.It has also been proposed that elongated sleeves of the charactermentioned be made by injection molding; however this technique requiresthe use of a precisely made single cavity mold which is located in anexpensive injection molding press. Further, each of these injectionmolded sleeves must then be precisely cut to define a plurality ofindividual V-belts whereby the belts formed in this manner are also veryexpensive and not of optimum quality.

SUMMARY This invention provides an improved method of making a pluralityof individual power transmission belts, such as V- belts, in asimultaneous manner by injection molding so as to define belts ofoptimum quality and structural strength which do not vary from one beltto the next. The plurality of belts are formed utilizing a lowerstructure and an upper structure which are suitably fastened togetherand have cooperating surface means provided therein which define aplurality of annular cavities each defining an associated belt. Thecooperating surface means may be easily modified to define belts ofstandard configuration, thin belts, or toothed belts, for example.

Other details, uses, and advantages of this invention will becomeapparent as the following description of the exemplary embodimentsthereof presented in the accompanying drawings proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings show presentexemplary embodiments of this invention, in which FIG. 1 is afragmentary perspective view with parts in cross section illustrating anexemplary endless power transmission belt made by the method of thisinvention;

FIG. 2 is a perspective view of an exemplary apparatus used tosimultaneously form a plurality of three belts of different sizes andeach having a cross-sectional configuration similar to thecross-sectional configuration of the exemplary belt illustrated in FIG.1;

FIG. 3 is an enlarged fragmentary cross-sectional view taken essentiallyon the line 3-3 of FIG. 2 and with the top structure assembled inposition;

FIG. 4 is a plan view illustrating another exemplary embodiment of anapparatus utilized to make a plurality of two belts in side-by-siderelation in accordance with this invention and showing roughly half ofthe top structure of such mold broken away;

FIG. 5 is an enlarged fragmentary cross-sectional view taken essentiallyon the line 5-5 of FIG. 4;

FIG. 6 is a plan view of another exemplary apparatus employed in themethod of this invention and such apparatus is similar to the apparatusof FIG. 4 and showing roughly half of the top structure comprising suchapparatus broken away;

FIG. 7 is a view similar to FIG. 6 illustrating another exemplaryembodiment of an apparatus employed in the method of this invention andused to form a plurality of belts in a plurality of sets with each sethaving a plurality of concentric annular cavities defining acorresponding plurality of power transmission belts;

FIG. 8 is an enlarged fragmentary cross-sectional view taken essentiallyon the line 8-8 of FIG. 7;

FIG. 9 is a fragmentary perspective view illustrating an annular ringwhich may be used in any one of the apparatus of FIGS. 2, 4, 6, or 7 todefine a belt of comparatively small thickness; and

FIG. 10 is a fragmentary perspective view similar to FIG. 9 andillustrating an annular ring which may be used in any of the illustratedapparatus to define a belt having a toothed configuration in itscompression section.

DESCRIPTION OF ILLUSTRATED EMBODIMENTS Reference is now made to FIG. 1of the drawings, which illustrates a fragmentary portion of an exemplarypower transmission belt made using the method of this invention. Thebelt 15 comprises an outer fabric cover 16; a tension section 17adjoining and being bonded to the cover 16, with the tension section 17being defined by a gum material having high resiliency; a load-carryingsection comprised of a load-carrying cord 20 which adjoins the tensionsection 17 and is partially embedded therein; and a compression section21 made by injection molding and utilizing the method of this inventionand in a manner to be described in detail subsequently. The fabric cover16, tension 17, and load-carrying cord 20 may be preformed as a unit orouter section using any suitable known technique and such outer sectionwill be designated generally by the reference numeral 22.

The belt 15 may be made using any one of the various exemplary apparatusto be describe hereinafter; and the detailed description will proceed byfirst describing the apparatus 24 shown in FIGS. 2 and 3 of thedrawings. The apparatus or mold 24 comprises a lower structure 25 and anupper structure 26 which are held together using any suitable fasteningdevice and for ease of presentation in this example of the invention,the structures are shown held together by a plurality of threaded bolts27 each extending through an opening 30 in the upper structure 26 andbeing threadedly fastened in a threaded opening 31 in the lowerstructure 25. The threaded bolts 27 serve the dual purpose of holdingstructures 25 and 26 together and precisely aligning such structures toassure the precision simultaneous forming of a plurality of powertransmission belts similar to the belt 15.

The mold 24 has cooperating surface means provided in its structures 25and 26 which define a plurality of three annular cavities havingsubstantially identical cross-sectional configurations and differentlengths. For convenience and ease of presentation, each cavity will bedesignated by the reference numeral 32 and defines an associated beltupon injecting an elastomeric material therewithin in the manner to besubsequently described.

The lower structure 25 has a plurality of three annular rings ofcircular outline and such rings are designated by the reference numerals35, 36, and 37. Each ring 35-37 of this example is suitably fixed to alower member comprising the lower structure 25 by a plurality ofthreaded screws 41 whereby each of such rings is readily removable.

Each ring 35-37 has at least one surface thereof defining a wall orsurface of an associated cavity 32. In particular, ring 35 has an outersurface 42 defining one wall of the inner cavity 32, ring 36 has aninner surface 43 defining an opposite wall of the inner cavity 32 andhas an outer surface 44 which defines a wall of the center cavity 32,and ring 37 has an inner surface 45 arranged opposite surface 44 anddefining an opposed wall of the center cavity 32 and has an outersurface 46 defining the inner wall of the outer cavity 32.

The lowe member 40 of lower structure 25 has a plurality of spacedinclined annular surfaces 50, 51, 52, each defining a lower wall of anassociated annular cavity 32 and such surfaces are concentricallyarranged in spaced relation. The manner in which surfaces 50-52cooperate with associated rings 35-37 and associated surfaces of upperstructure 26 will be described in detail subsequently.

The upper structure 26 is comprised of an outer member 53 adjoined by amember 54 which is normally sandwiched between members 40 and 53 areheld in position by the threaded bolts 27. The member 53 has a centralsprue 55 and a plurality of radial grooves 56 formed therein whichcommunicate with the sprue 55 and upon installing members 53 and 54together the grooves 56 cooperate with the top surface 57 of member 54todefine radial runners and for convenience such radial runners willalso be referred to as runners 56.

The member 54 has an outer surface which is provided with a plurality ofinclined annular surfaces 60, 61, and 62 which are concentricallyarranged in spaced relation. The surface 60 cooperates with surfaces 42,50, and 43 to define the inner annular cavity 32; surface 61 cooperateswith surfaces 44, 51, and 45 to define the center annular cavity 32; andsurface 62 cooperates with surfaces 46, 52, and a cylindrical surface 63provided in member 40 to define the outer cavity 32.

The mold 24 has passage means for flowing elastomeric material in eachmold cavity and such passage means comprise a plurality of annularrunners each associating with a particular mold cavity 32 provided inthe lower structure 25 and for convenience each annular runner will bedesignated by the reference numeral 64. The mold 24 also has a pluralityof annular slits 65 each placing an associated groove or runner 64 influid flow communication with am associated annular cavity 32. Each slit65 is provided by cutting an annular strip from the outer top portion ofan associated annular ring 35-37 which extends from an annular runner 64to its associated outside surface 42, 44, and 46 respectively for rings35, 36, and 37.

The mold 24 also has a plurality of interconnecting vertical channels 66provided in member 54 of its lower structure 25 and each channel 66connects a radial runner 56 with an associated annular runner 64 and itsslit 65. Thus, it is seen that flow of elastomeric material is providedthrough sprue 55, radial runners 56, vertical channels 66 annularrunners 64, and slits 65 to simultaneously fill the three annularcavities 32 after placing outer sections 22 in position tosimultaneously define a plurality of three belts 15 having substantiallyidentical cross-sectional configurations and different lengths. Thesprue 55 may be supplied with elastomeric material from any suitablesource through a conduit 67, as seen in FIG. 3.

After elastomeric material has been injected into the mold cavities 32such material is suitably cured and cooled using any known technique andthe three belts 15 are removed from the mold 24. Each belt 15 will haveflash material adjoining a corner of its compression section 21 and suchflash material is comprised of the material present in the annularrunner 64 and slit means 65 of the particular belt prior to removal ofsuch belt from the mold 24. The flash material is trimmed using anysuitable technique and trimming device.

In this example of the invention the elastomeric material is injectedinto each cavity 32 through annular slits which enter a corner of themold cavity throughout its entire peripheral outline. However, it willbe appreciated that the passage means in mold 24 may be such that flowof elastomeric material may be introduced into the mold cavities atlocations other than the corners thereof. In addition, flow may beprovided into each mold cavity through a plurality of spaced passages tothereby simultaneously form a plurality of individual power transmissionbelts of optimum quality.

Another exemplary embodiment of an apparatus which may be used incarrying out the method of this invention is illustrated in FIGS. 4 and5 of the drawings. The apparatus illustrated in FIGS. 4 and S is verysimilar to the apparatus 24; therefore, such apparatus will bedesignated generally by the reference numeral 24A and parts of theapparatus 24A which are very similar to corresponding parts of theapparatus 24 will be designated by the same reference numeral as theapparatus 24, also followed by the letter designation A" and notdescribed again. Only those component parts which are substantiallydifferent from corresponding parts of the apparatus 24 will bedesignated by a new reference numeral, also followed by the letterdesignation A" and described in detail.

The main difference between the apparatus 24 and the apparatus 24A isthat the apparatus 24A instead of having a plurality of concentricannular cavities provided therein for the forming of a correspondingplurality of transmission belts having different sizes, i.e., perpheraloutlines or lengths, provides for the forming of a plurality of twoequal length transmission belts in side-by-side relation and suchtransmission belts are formed so that each has an oval configuration asillustrated at 70A. By forming each transmission belt so that it has anoval configuration it is possible to provide a plurality of two belts,for example, approximately within the volume or space which wouldnormally be utilized to define a single belt of the same size and to acircular configuration and this fact is highlighted by the circulardotted lines shown at 71A in FIG. 4.

The mold 24A has a lower structure 25A comprised of a lower member 40Aand a plurality of identical annular rings 73A each fastened in positionby a plurality of fastening screws 74A. The member 40A has a pair ofcylindrical surfaces 75A of oval outline and each surface 75A isadjoined by an inclined annular surface 76A provided in member 40A.

The intermediate member 54A of the upper structure 26A of mold 24A alsohas a plurality of two inclined annular surfaces 77A formed therein. Aset of surfaces 75A, 76A, and 77A cooperate with the outside surface 80Aof an associated readily detachable annular ring 73A to define anannular cavity 81A within which a power transmission belt is made byinjection molding and such belt is substantially identical to the beltIS with the exception that it is initially formed by mold 24A in ovalform. However, once the elastomeric material injected into each cavity81A has been suitably cured and cooled and the resulting belt removedfrom its mold, it will have circular form.

Elastomeric material is introduced into the sprue 55A of mold 24Athrough a conduit 67A whereupon such material flows through runners 56A,interconnecting channels 66A, annular runners 64A, and annular slits 65Ainto the cavities 81A. Thus, a plurality of two individual belts ofequal length may be formed in a simultaneous manner by injection moldingin the mold 24A in a similar manner as described for belts of differentlengths formed in the mold 24.

A modification of the mold 24A is illustrated in FIG. 6 and thereforesuch modification will be designated by the reference numeral 248. Themain difference between the mold 24B and the mold 24A is that thecooperating surface means provided in the mold 248 are such that each ofthe two annular cavities 81A has side portions which are arranged inparallel relation. With this exception, the remainder of the mold ofFIG. 6 is identical to the mold of FIGS, 4 and 5 whereby componentportions thereof are designated by the same reference numerals as in themold 24A and a detailed description of the mold 245 will not be made, itbeing understood that reference may be made to the previous descriptionof mold 24A for an understanding of the detailed construction of themold 248. The arrangement of side portions of each cavity 81A inparallel relation enables forming a plurality of belts 15 of equallength in a mold having a smaller width.

Another exemplary embodiment of an apparatus which may be used incarrying out the method of this invention is illustrated in FIGS. 7 and8 of the drawings. The mold illustrated in FIGS. 7 and 8 is very similarto the mold 24A; therefore, such mold will be designated generally bythe reference numeral 24M and parts of the mold 24M which are verysimilar to corresponding parts of the mold 24A will be designated by thesame numeral as in the mold 24A also followed by the letter designationM and not described again. Only those component parts which aresubstantially different from corresponding parts of the mold 24A will bedesignated by a new reference numeral also followed by the letterdesignation M" and described in detail.

The mold 24M is comprised of a lower structure 25M and an upperstructure 26M; however, the annular mold cavities 81M defined in themold 24M comprise a plurality of two sets of oval cavities asillustrated at 85M and at 86M in FIG. 7. Each set 85M and 86M has aplurality of oval cavities 81M arranged therein in a substantiallyconcentri manner whereby the advantages of being able to define aplurality of cavities in a mold of given size as illustrated inconnection with the apparatus 24A are combined with the advantages ofutilizing a mold similar to the mold 24 having concentric cavities tothereby provide the best features of both structures.

The lower structure 25M of the mold 24M is comprised of a pair ofannular rings 73M suitably held in position by fastening screws 74M anda plurality of rings 90M also held in position by screws 74M. The rings90M are similar in function to the rings 36 and 37 comprising the mold24. Each ring 90M has opposed surfaces 91M and 92M with inside surface91M cooperating with an inclined surface 93M of member 40M, an outersurface 80M of ring 73M, and inclined annular surface 95M of member 54Mto define the inner mold cavity 81M of each set, either set 85M or 86M.The outside surface 92M of ring 90M cooperates with an inclined annularsurface 100M and an adjoining cylindrical surface 101M of oval outlinein member 40M together with an inclined surface 102M in member 54M todefine the outer mold cavity 81M of each set 85M or 86M.

As previously an elastomeric material is introduced into mold 24Mthrough a common sprue 55M. Each cavity 81M is supplied by an annularslit 65M which communicates with an annular runner 64M which in turncommunicates with an associated interconnecting passage 66M and asubstantially radial runner 56M. Thus, elastomeric material isintroduced into each cavity 81M in a simultaneous manner to enablefilling both sets 85M and 86M of cavities 81M to thereby individuallyform a plurality of high quality belts 15 in a simultaneous manner.

Each belt 15 formed in the mold 24M has an outer section 22M which isplaced in position in an associated mold cavity 81M in a similar manneras previously described in connection with mold 24; therefore, suchdescription will not be repeated.

The power transmission belts formed utilizing the apparatus or molds 24,24A, or 24M may be considered as being belts of standard thickness;however, it will be appreciated that the technique of this invention maybe utilized to form what may be considered thin belts or belts eachhaving a reduced vertical thickness as indicated at 103 in FIG. 9. Thismay be achieved either by utilizing an annular ring 104 for each thinbelt 15A which is similar to the corresponding rings of the previouslydescribed molds but having a radial thickness 105 which is greater thanthe corresponding thickness for a ring used to make a standard belt. Itwill also be appreciated that the various surfaces of a ring 104 for athin belt may be comprised of a plurality of cooperating annularsections one of which may be the ring used to form a V-belt of standardsize and with suitable cooperating passage means provided in suchannular sections to enable injection of the elastomeric material intothe mold cavity.

The method of this invention may also be used to define a plurality oftoothed belts and for this purpose a plurality of rings similar to thering 106 illustrated in FIG. may be provided, with each ring 106 beingfully interchangeable with a standard ring provided in an associatedmold. Each ring 106 preferably has means for placing the outer portionthereof in fluid fiow communication with its associated annular moldcavity. Preferably, each ring 106 has an annular runner 107 providedwith radial openings 110 which place the runner 107 in communicationwith the crest of each tooth of an associated toothed belt 158. Thus,not only is the method of this invention applicable to the simultaneousforming of a plurality of individual belts of standard construction, butsuch method is fully applicable to forming toothed belts as well as whatmay be considered thin belts.

The belts 15, A, and 15B are shown as being formed in what may beconsidered their normal positions and cooperating surface means havebeen provided in each mold to enable forming such belts in their normalpositions. However, it will be appreciated that the method of thisinvention is fully applicable to the forming of belts by injectionmolding and in their inverted positions. Thus, after suitably curing andcooling belts formed in their inverted positions, each belt would betrimmed of flash material, inverted, and utilized in the normal manner.

In this disclosure, only the compression section of each belt is formedby injection molding. After the outer section (comprised of an outerfabric, a tension section, and a load-carrying cord) has been placed inposition in its associated mold cavity. However, it will be appreciatedthat the technique of this invention is fully applicable when the entirebelt cross sections of a plurality of belts are formed by injectionmolding.

To assure easy understanding of this invention, the disclosure presentsthat the mold halves are held together by bolts. However, it is to beunderstood that in normal practice the mold halves are positioned in apress with the illustrated bolts replaced by centering pins. These pinsalign the mold as the press closes and the clamping force which holdsthe mold halves together comes from the injection press itself.

While present exemplary methods of practicing this invention, have beenillustrated and described, it will be recognized that this invention maybe otherwise practiced within the scope of the following claims.

What is claimed is:

l. A method of simultaneously making a plurality of individual powertransmission belts comprising the steps of forming a plurality ofannular mold cavities in a mold comprised of an upper structure fastenedto a lower structure by detachably fastening a plurality of annularrings in said mold corresponding in number to the number of cavities insaid mold, each of said rings having at least one surface which definesa corresponding wall of an associated mold cavity, placing an annularinsert in each mold cavity, each insert having an integral load-carryingportion and defining a corresponding outer section in its associatedbelt, injecting an elastomeric material in a simultaneous manner intosaid plurality of mold cavities by injecting through radial runners, andcuring and cooling said elastomeric material to define said plurality ofbelts.

2. A method as set forth in claim 1 in which said injecting stepcomprises injecting said elastomeric material into said mold cavitiesusing a plurality of annular runners corresponding in number to saidplurality of mold cavities, each of said annular runners being in flowcommunication with an associated mold cavity and said radial runners.

3. A method as set forth in claim 1 in which said step of detachablyfastening comprises fastening at least one ring in said mold having anincreased radial thickness which enables forming an associated beltwhich is thinner than a standard belt.

4. A method as set forth in claim 1 in which said step of detachablyfastening comprises fastening at least one ring in said mold having onesurface in the form of a toothed surface which enables forming anassociated belt having a corresponding toothed surface.

5. A method as set forth in claim 1 in which said forming step comprisesforming a plurality of oval cavities in said mold having equal lengthsand being arranged in side by side relation to thereby enable thesimultaneous making of a corresponding plurality of individual beltshaving equal lengths.

6. A method as set forth in claim 5 in which said forming step comprisesforming said plurality of oval cavities substantially in the same plane.

7. A method as set forth in claim 1 in which said forming step comprisesforming a plurality of concentric cavities in said mold having difierentlengths to thereby enable the simultaneous making of a correspondingplurality of individual belts having different lengths eachcorresponding in length to its associated cavity.

8. A method as set forth in claim 7 in which said forming step comprisesforming said plurality of concentric cavities substantially in the sameplane.

9. A method as set forth in claim 1 in which said forming step comprisesforming a plurality of sets of cavities in said mold, said sets ofcavities being arranged in side-by-side relationship and each setcomprising a plurality of concentric cavities.

1. A method of simultaneously making a plurality of individual powertransmission belts comprising the steps of forming a plurality ofannular mold cavities in a mold comprised of an upper structure fastenedto a lower structure by detachably fastening a plurality of annularrings in said mold corresponding in number to the number of cavities insaid mold, each of said rings having at least one surface which definesa corresponding wall of an associated mold cavity, pLacing an annularinsert in each mold cavity, each insert having an integral load-carryingportion and defining a corresponding outer section in its associatedbelt, injecting an elastomeric material in a simultaneous manner intosaid plurality of mold cavities by injecting through radial runners, andcuring and cooling said elastomeric material to define said plurality ofbelts.
 2. A method as set forth in claim 1 in which said injecting stepcomprises injecting said elastomeric material into said mold cavitiesusing a plurality of annular runners corresponding in number to saidplurality of mold cavities, each of said annular runners being in flowcommunication with an associated mold cavity and said radial runners. 3.A method as set forth in claim 1 in which said step of detachablyfastening comprises fastening at least one ring in said mold having anincreased radial thickness which enables forming an associated beltwhich is thinner than a standard belt.
 4. A method as set forth in claim1 in which said step of detachably fastening comprises fastening atleast one ring in said mold having one surface in the form of a toothedsurface which enables forming an associated belt having a correspondingtoothed surface.
 5. A method as set forth in claim 1 in which saidforming step comprises forming a plurality of oval cavities in said moldhaving equal lengths and being arranged in side by side relation tothereby enable the simultaneous making of a corresponding plurality ofindividual belts having equal lengths.
 6. A method as set forth in claim5 in which said forming step comprises forming said plurality of ovalcavities substantially in the same plane.
 7. A method as set forth inclaim 1 in which said forming step comprises forming a plurality ofconcentric cavities in said mold having different lengths to therebyenable the simultaneous making of a corresponding plurality ofindividual belts having different lengths each corresponding in lengthto its associated cavity.
 8. A method as set forth in claim 7 in whichsaid forming step comprises forming said plurality of concentriccavities substantially in the same plane.
 9. A method as set forth inclaim 1 in which said forming step comprises forming a plurality of setsof cavities in said mold, said sets of cavities being arranged inside-by-side relationship and each set comprising a plurality ofconcentric cavities.